1. Field of Invention
The present invention belongs to the field of power electronic technology, and relates to a driving circuit, in particular to a bootstrap driving circuit without an extra power supply.
2. Description of Related Arts
With the development of the power electronic technology, a power level of a power electronic converter continually improves; driving energy of a power device continually increases as well. In principle, each controllable power switch requires its own isolated drive power, which results in the requirement of an isolated power supply. The isolated power supply includes a linear power supply and a switching power supply. The more the number of the isolated power supplies is, the greater difficulty the design of the isolated power supplies is, thereby causing the increase of cost and size, and even affecting the work efficiency of the system.
An existing bootstrap driving circuit, as shown in FIG. 1, includes a control chip, wherein a bootstrap diode is connected between a high-side switch driver output power supply terminal of the control chip and a power supply, a bootstrap capacitor is connected between the high-side switch driver output power supply terminal and a low-side switch driver output power supply terminal; the high-side switching pulse output end and the low-side switching pulse output end of the control chip is connected with a high-side switching MOS transistor and a low-side switching MOS transistor, respectively; the source electrode of the high-side switching MOS transistor and the drain electrode of the low-side switching MOS transistor are connected as a driving output end, which is further connected with the low-side switch driver output power supply terminal; an additional power supply circuit is connected between the source electrode of the high-side switching MOS transistor and the power supply terminal of the two switch driving output circuit.
From the existing bootstrap driving circuit, it is known that drive units of the conventional power device need an extra power supply, which results in insufficient application range, inflexible usage and high cost. With the expansion of the practical application, more and more power devices need the drive of the drive units, and conventional bootstrap driving circuit has been increasingly unable to meet the demand. Therefore, it is imperative for persons skilled in the art to design a bootstrap driving circuit with a simple structure, fully function and without an extra power supply.